How to solve my statistics question? someone please help me!

Posted on 2014-12-05 05:51:00 in Statistics by MIKE

1. Why do larger sample sizes produce narrower confidence interval?

2. The purpose of a confidence interval for µ is _________________ .

a) to give a range of likely values for the unknown population mean.
b) to give a range of likely values for the level of confidence.
c) to give a range of likely values for the sample mean.
d) to give a range of likely values for the difference between the sample mean and the population mean.

3. A large school district in Connecticut wants to estimate the average SAT score of this year’s graduating class using a 95% confidence interval. The district takes a simple random sample of 100 seniors. The sample mean is 300 and the population standard deviation for SAT scores is known to be 100. What is the 95% confidence interval for m?

a) 300 ± 1.96(100)
b) 300 ± (100/10)
c) 300 ± 1.96(100/10)
d) 300 ± 1.96(100)(10)

4. If you are doing a statistical test with alpha=.05 and beta=.20, what is your power?

5. Laurie has concluded that the difference between the means of sophomores and freshmen is significant, when in fact the null hypothesis is true. What type of error has she committed?

6. The lead content of a specific brand of toy is to be studied. The Consumer Product Safety Commission requires that the mean lead content be less than 300 ppm. They want to design a study that will have at least 95% probability of rejecting the null hypothesis at the significance level of 0.01 when the true mean lead content is 325 ppm is higher.

What is the ‘probability of a Type I error’ in this example?

a) 0.05
b) 0.01
c) 0.10
d) 0.95

7. Which of the following defines Type II error?

a) Reject Ho when Ho is true.
b) Reject Ho when Ho is false.
c) Do not reject Ho when Ho is true.
d) Do not reject Ho when Ho is false.

8. The manufacturer of a certain toy claims that the mean lead content in this toy is 100 ppm. A sample of 100 such toys produced mean= 110 ppm. This would provide evidence against the manufacturer’s claim if we can show that _____________.

a) 105.1 could reasonably occur by chance if the claim were true
b) 105.1 could rarely occur by chance if the claim were true
c) 100 could rarely many occur by chance if the claim were true
d) 100 could reasonably occur by chance if the claim were true

---

Answer Comment

No Answers Posted Yet.